Apparatus for annealing coils of steel strip



W5 R. w. WIGG 3,169,][

APPARATUS FOR ANNEALING cons OF STEEL STRIP Filed June 28, 1961 WI: 'wlulh uwnu oswouvr a ma 1. r251;

Steam Condensate Gas I/V I/E-IV 70/? Attorney Unit This invention relates to apparatus for annealing coils of steel strip and more particularly to increasing the moisture in the atmosphere gas supplied to the coils during annealing. Atmosphere gas such as burned natural gas and mixtures of hydrogen'and nitrogen or mixtures of hydrogen, carbon monoxide and nitrogen are used in annealing for various purposes. The gas may be used in decarburizing in which case the moisture content of the gas is important for increasing the decarburizing effect. For further discussion of various treatments and atmospheric gases, attention is directed to an article by Arnold entitled Open Coil Process starting on page 91 of the August 1960 issue of Iron and Steel Engineer. The common way of producingfa high dew point protective atmospheric gas is to inject steam therein. However, this manner of injection has various difliculties including the difficulty of control of the moisture content.

It is therefore an object of my invention to provide apparatus for annealing coils of steel strip wherein the control of the dew point of the atmosphere gas is accurate.

Another object is to provide apparatus for adding moisture to an atmosphere gas which is simple to install and to control.

These and other objects will be more apparent after referring to the following specfication and attached drawing, in which:

The single figure is a schematic view showing the apparatus of my invention.

Referring more particularly to the drawing reference d States Patent The parts so far described are conventional and are preferably associated with open coil annealing as shown and dc scribed in the Arnoldarticle. The atmosphere gas is delivered to pipe 8 though a conduit 14 having a valve 16 therein. A branch conduit 18 has one end connected to conduit 14 on the entry side of the valve 16 and the other end connected to conduit 14 on' the exit end of valve 16. A heating zone 20 is provided in the conduit 18 for raising the temperature of the atmosphere gas so that it can'have a higher dew point and. hold a greater amount of moisture. As shown, the heating zone 20 includes a section 21 of the conduit with insulation 22 around it. A heating element 24 is inserted through a T 26 into the conduit section '21. A thermostat 28 is inserted into a T 30 on the exit side of the heating element 24 and is provided with a contact 28C. A mixing T 32 is arranged in conduit 18 on the exit side of T 30 and a U-tube 34 arranged generally vertical has the top of its leg '36 connected to the 'T 32 and its other leg 38 open to atmosphere. Steam condensate is-delivered into the top ofleg 38 through a conduit 40. A T 42 is provided at the top of leg 38-andhas a side outlet 44 so that overflow of the condensate can be observed. A T 46 is arranged at the bottom of leg 36 and an immersion heater 48 is inserted therethrough. A valve 50 is provided'in conduit 18 on the entry side of heating zone 21) and a valve 52 is provided in conduit 18 on the exit side of mixing T 32. A conduit 54 is connected to thepipe 10 and is provided with a sample collecting line 56. Power for heating elements 24 and 48 i is provided from a 120 volt A.C. source L1, L2. A push button switch 58 controls flow of current to the heating element 24 through contact 280. A push button switch 60 controls flow of current to heater 48 through an auto transformer 62' and ammeter 64. The portion of arm 62A of auto transformer 62 is controlled by means of a standard controller 66 operated from a standard dew point analyzer 68 connected 'to line 56.

In operation, when it is desired to add moisture to the atmospheric gas, valves 50 and 52 are opened, valve 16 is then closed, and push button switches 58 and 60 closed. Steam condensate is delivered through conduit 40 into leg 38. If steam condensate is not available ordinary water may be used. However, it is preferred to use steam condensate because of its purity. The flow of condensate to the U-tube 34 and the amount of heat provided by heater 48 may be readily controlled so that the quantity of water entering the gas can be accurately determined. The position of arm 62A can be accurately controlled by the dew point analyzer 68 so as to obtain the desired heat input 'to the water in leg 36. The temperature of the atmosphere gas can also be controlled accurately by means of the immersion heater 24 and thermostat 28. Assuming that the steel is being decarburized a sample of the gas leaving the furnace can be obtained through sampling tube 56 and when the outlet dew point equals inlet dew point and the outlet hydrogen equals inlet hydrogen and the carbon monoxide content is zero the decarburization is considered complete. The valves 50 and 52 are then shut oif and valve 16 opened so that the annealing cover 6 can be purged with dry atmospheric gas. While one embodiment of my invention has been shown and described, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. Apparatus for annealing coils of steel strip comprising means for supporting a coil of strip, a cover for enclosing said supported coil of strip, a conduit for delivering a heat treating atmosphere gas to the coil of strip within said cover, a U-tube having two substantially vertical legs and a connection between the lower ends of said legs, said vertical legs and said connection containing water, means connecting the upper end of the first of said legs to said conduit, means for supplying water to the second leg of said U-tube, and means for supplying heat to the water in the first of said legs to vaporize the same and cause it to rise into the atmosphere gas in said conduit.

2. Apparatus for annealing coils of steel strip comprising means for supporting a coil of strip, a cover for enclosing said supported coil of strip, a conduit fordelivering a heat treating atmosphere gas to the coil of strip within said cover, a valve in said conduit, a branch conduit having its ends connected to said first named conduit one end on each side of said valve, a U-tube having two substantially vertical legs and a connection between the lower ends of said legs, said vertical legs and said connection containing water, means connecting the upper end of the first of said legs to said branch conduit, means for controlling flow of atmosphere gas through said branch conduit, means for supplying water to the second leg of said U-tube,

means for supplying heat to the water in the first of said legs to vaporize the same and cause-it to rise into the atmosphere gas in said branch conduit, and an outlet conduit for removing atmospheregas from said cover.

3. Apparatus according to claim 2 including means for analyzing a sample of said atmosphere gas from said outlet conduit for moisture content, and means operable by said analyzing means for controlling the operation of said vaporizing means whereby the desired amount or" moisture I is added to the atmosphere gas.

4. Apparatus according to claim 2 in which the vaporizing means is an immersion heater in said first leg and the water addition is steam condensate.

5. Apparatus according to claim 4 including means for analyzing a sample of said atmosphere gas from said outlet conduit for moisture content, and means operable by said analyzing means for controlling the operation of said immersion heater whereby the desired amount of moisture is added to the atmosphere gas. a

6. Apparatus for annealing coils of, steel strip comprising means for supporting a coil of strip, a cover for. enclosing said supported coil of strip, a conduit for delivering a heat treating atmosphere gas'to the coil of strip within said cover, a valve in said conduit, a branch conduit having its ends connected to said first named conduit one end on each side of said valve, means for heating said atmosphere gas in said branch conduit, a valve in said branch conduit on the entry side of said heating means, a T connection in said branch conduit on the exit side of said heating means, a U-tube having two substantially vertical legs and a connection between the lower ends of said legs, said vertical legs and said connection containing water, means connecting the upper end of the first of said legs to said T connection, an immersion heater in said first leg, means for supplying steam condensate to the upper end of the second leg of said U-tube, overflow means connected to said second leg adjacent the top f References Cited by the Examiner 'UNITED STATES PATENTS 167,395 9/75 Franke 126-113 1,697,115 1729 Hargreaves. v 1,919,861 7/33 Rodhe 23-254 X 1,983,294 12/34 Huttenmiller. t 2,161,162 6/39 Harsch 266-5 2,215,645 9/40 Iredell et a1 266-5 2,347,490 4/44 Legeman 236-44 2,395,385 2/46 Green et a1. 266-26 2,556,962 6/51 Field 266-5 7 3,063,878 11/62 Wilson -1. 266-5 X 3,094,468 6/ 63 Topham 23-292 X MORRIS O. WOLK, Primary Examiner. RAY K. WINDHAM, Examiner. 

1. APPARATUS FOR ANNEALING COILS OF STEEL STRIP COMPRISING MEANS FOR SUPPORTING A COIL OF STRIP, A COVER FOR ENCLOSING SAID SUPPORTED COIL OF STRIP, A CONDUIT FOR DELIVERING A HEAT TREATING ATMOSPHERE GAS TO THE COIL OF STRIP WITHIN SAID COVER, A U-TUBE HAVING TWO SUBSTANTIALLY VERTICAL LEGS AND A CONNECTION BETWEEN THE LOWER ENDS OF SAID LEGS, SAID VERTICAL LEGS AND SAID CONNECTION CONTAINING WATER, MEANS CONNECTING THE UPPER END OF THE FIRST OF SAID LEGS TO SAID CONDUIT, MEANS FOR SUPPLYING WATER TO THE SECOND LEG OF SAID U-TUBE, AND MEANS FOR SUPPLYING HEAT 